Field of the Invention
This invention relates generally to the field of wireless communication; and more particularly, to components used in tuning circuits and methods of dynamically adjusting RF communication system performance.
Description of the Related Art
As the need for higher data rates increases, communication systems are being designed to cover wider instantaneous frequency bandwidths. Also, with the introduction of 4G protocols such as Long Term Evolution (LTE), additional frequency bands are being used for cellular communication systems. In mobile communication systems, backward compatibility is required for cell phones being designed for 4G LTE applications such that the cell phone must be capable of operating at the 2G and 3G cellular bands as well as the 4G frequency bands. In addition, LTE as a protocol is configured to accommodate carrier aggregation, where multiple channels can be transmitted or received on simultaneously to increase instantaneous bandwidth. This aggregation of channels can cover up to five channels spread across multiple frequency bands. All of these trends point toward a growing need for more flexibility in the RF front-end of mobile communication systems to address the combining of multiple frequency bands and modes.
Dynamic tuning of antennas and RF front-ends of communication systems is picking up adoption in the commercial communications industry, and proper implementation of dynamic tuning methods can bring improvements to communication system performance as the number of frequency bands that can be accessed grows and the instantaneous bandwidths required increases. As antennas in mobile communication systems transition from passive types to active antenna systems, look-up tables and/or algorithms will be required to control the antenna tuning. Open loop antenna tuning will require a look-up table which contains tuning state information as a function of frequency, use case, and other sensor information. Closed loop antenna tuning will require an algorithm to control components to converge to a matched condition for impedance tuning, or will require an algorithm to select the optimal radiation pattern in a smart antenna or beam-steering antenna system. Look-up tables and algorithms require memory to store the information. The look-up table or algorithm can be stored in memory at a location within the host device that the active antenna system or RF front-end is integrated into. The latency of the signaling to control the active antenna system or RF front-end will be dependent on the location of the memory available for the look-up table or algorithm, and will also be dependent on the communication bus used in the communication to control functionality.
Integrating active antenna systems and/or tunable RF front-end systems require an added step of loading information in the form of a look-up table or algorithm in memory of the host device. The latency of the tuning function needs to be determined based upon the host system design and the location of the memory used for information storage. For more complex communication systems where there might be an active antenna system and multiple tuning functions associated with an RF front-end module, multiple components will require memory from the host device. There is a need for simplifying the memory requirements as more tuning type circuits are integrated into communication systems. The enclosed embodiments address this problem and provide a unique set of capabilities to improve system performance along with simplifying the integration process.